Study to Determine the Efficacy&Safety of ARV-1801(ACG-701) for the Treatment of Cystic Fibrosis Pulmonary Exacerbations

Inclusion Criteria: 1. Males and females of 12 years of age and older 2. Participants must have a confirmed diagnosis of Cystic Fibrosis with a diagnosis of an acute pulmonary exacerbation as defined as: 1. Deterioration in 3 or more of the following symptoms for at least 48 hrs (cough, sputum volume and/or consistency, sputum purulence, breathlessness and/or exercise tolerance, fatigue and/or malaise, or hemoptysis) And 2. a clinician determines that a change in CF treatment is required 3. Participants must have a CFRSD-CRISS score of \>/= 35 4. Participants must have a moderate or Severe Patient Global Impression of Severity 5. Participants must have a negative pregnancy test and agree to use a highly effective method of contraception during the study and 30 days after last dose 6. Participants must agree not to smoke during any part of the clinical trial 7. Participants must voluntarily sign the informed consent for the study Exclusion Criteria: 1. Participants cannot have any changes in any antimicrobial, bronchodilator, anti-inflammatory, CFTR modulator or corticosteroid medications from 28 - 3 days prior to the Screening visit. 2. Participants cannot be receiving treatment for non-tuberculosis mycobacteria and/or Aspergillus infection. 3. History of hypersensitivity or allergic reaction to sodium fusidate, fusidic acid (Fucidin®) or its excipients. 4. Abnormal laboratory findings or other findings or medical history at Screening that, in the Investigator's opinion, would compromise the safety of the participant or the quality of the study data. 5. The use of an investigational drug or device (ie, a drug or device without the FDA approved indication) within 30 days prior to the Screening visit 6. Known severe renal impairment, as indicated by estimated creatinine clearance (CrCl) \<30 mL/min (by Cockcroft-Gault calculation). 7. Evidence of significant liver disease: ALT \>3×ULN, or direct bilirubin \>ULN, or total bilirubin \>1.5 mg/dL; known cirrhosis with decompensation (ie, Child-Pugh Class B or C disease). 8. Known hepatitis C virus (HCV) or infection and currently receiving HCV-specific antiviral therapy. HCV infection alone, and in the absence of decompensated liver disease, is not exclusionary. 9. Neutropenia (absolute neutrophil count \<500/µL); thrombocytopenia (\<60,000 platelets/mm3). 10. Known human immunodeficiency virus (HIV) infection and currently receiving antiretroviral therapy, or current CD4 count ≤200 cells/mm3 (documented within 3 months prior to enrollment); if CD4 count is unknown, participant may not enroll. 11. Changes to or initiation of immunosuppressant agents (ie, prednisone \[≥15mg/day\], cyclosporine, tumor necrosis factor alpha \[TNFα\] antagonist) within 30 days of study medication administration through the EOS visit. 12. Malignancy requiring ongoing cytotoxic chemotherapy or radiation therapy. 13. Requires concomitant treatment with (washout period prior to randomization allowed): * OATP1B1 and OATP1B3 substrates (eg, HMG-CoA reductase inhibitors \[statins\]) * CYP2C8 substrates, namely glitazones (eg, repaglinide) * CYP3A4 inducers (eg, dexamethasone, phenytoin, carbamazepine, rifampin, phenobarbital, nafcillin) * Moderate/strong CYP3A4 inhibitors (eg, azole antifungals, erythromycin, clarithromycin) * P-gp substrates with narrow therapeutic windows (eg, digoxin and colchicine) 14. Prior treatment with a CYP3A4 inducer (such as lumacaftor, dexamethasone, phenytoin, carbamazepine, rifampin, phenobarbital and nafcillin) within 7 days prior to enrollment. 15. Dietary use of large amounts of grapefruit juice and/or Seville oranges or other products containing these fruits (eg, grapefruit juice or marmalade) during the study. 16. Participant requiring warfarin therapy. 17. Seizure disorder requiring current therapy with an anticonvulsant. 18. Female participant who is pregnant or lactating. 19. History of /current chronic alcohol consumption and/or drug abuse (including cannabis use). 20. Any study personnel or their immediate dependents, family, or household members.